Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #6 Mar 31 2012 12:36:22
%S 1,7,43,268,1740,11862,85013,639760,5045610,41615165,358185399,
%T 3210667490,29914284833,289187621900,2895861006415
%N Number of lower triangles of a (2n-1)X(2n-1) 0..n array with new values introduced in row major order 0..n and no element unequal to more than one horizontal or vertical neighbor
%C Row 1 of A194778
%e All solutions for n=2 containing a 2
%e ..0
%e ..1.1
%e ..1.1.2
%K nonn
%O 1,2
%A _R. H. Hardin_ Sep 02 2011